import pygame, sys, random
pygame.init()
screen = pygame.display.set_mode([640,480])
screen.fill([255,255,255])
for i in range (100):
    width = random.randint(0, 250)
    height = random.randint(0, 100)
    top = random.randint(0, 400)
    left = random.randint(0, 500)
    pygame.draw.rect(screen, [0,0,0],[left,top,width,height], 1)
    pygame.display.flip()
    pygame.time.delay(30)
